1. Field of the Invention
This invention relates to electrical circuits and, more particularly, to current mirrors.
2. Description of the Related Art
Integrated circuits often use current mirrors when it is desired to replicate a current from a first portion of a circuit to a second portion. Two typical problems with such current mirrors include Early effect, resulting in a difference between input and output currents as a result of a difference between input and output voltages, and beta error, the difference between input and output currents when no difference in input and output voltages exists.
One attempt to reduce these errors is illustrated in U.S. Pat. No. 6,194,886. In this patent, a compensation circuit has two compensation stages connected to either side of an output stage of the current mirror to, in response to a change in output voltage, provide a change of current to the output of the output stage to reduce Early effect and beta error. Unfortunately, the compensation circuit requires the addition of three transistors to provide the response to the current mirror.
A need still exists for reducing Early effect and base current errors in current mirrors without adding unnecessary components.